What do the FSA indicators in the Materiality Column mean?

What do the FSA indicators in the Materiality Column mean?

The indicators within the FSA worksheet are used to determine the amount of work the auditor needs to do or has done in relation to materiality.
The red indicator will appear in the Materiality Assessment column if the planning balance is not materialand the final balance is material. This indicates that there is a risk of insufficient audit work. 
The yellow indicator will appear in the Materiality Assessment column if the planning balance is material and the final balance is not material. This indicates that there is a risk of over-auditing.